The invention relates to a circuit arrangement for the time division multiplex (t.d.m.) transmission of asynchronously occurring binary values of data, in which in the frame of a relatively coarse sampling pulse train, i.e., a sampling pulse train having a repetition frequency less than the system sampling interval, each change in binary value is assigned a pulse group comprising a plurality of bits. In this arrangement the data are conducted to a binary value change discriminator which following the occurrence of a change in binary value, and upon the arrival of a scanning or sampling signal, emits a write-in command which causes the pulse group to be coupled into a register.
If the charges in binary value of the binary values which are to be transmitted occur asynchronously, and thus at an arbitrary time, a technique know as "multiple scanning and coding with sliding index" can be used to bring such binary values into phase with a transmitting-end t.d.m. transmission system. This technique contemplates that a given binary value be sampled a number of times and that a pulse group containing a number of bits determined by the duration of the binary value be formed. Then, at the transmitting end in the frame of a coarse sampling pulse train each binary value change causes the production of a pulse group comprising a plurality of bits, and this pulse group is transmitted within a t.d.m. signal. This type of pulse group can, for example, consist of three bits which at the transmitting end are fed in serial fashion into the t.d.m. system. This serial feeding-in of the pulse group is carried out during the emission of a plurality of coarse scanning pulse trains and during the duration of the individual binary values. Generally speaking, the feeding-in of the pulse group will have terminated before the occurence of the next change in binary value. This is in particular the case when undistorted data binary values exist. If, however, individual distorted binary values occur, it can come about that the next change in binary value will occur before the pulse group has been fed in, and thus, an incorrect pulse group is emitted.
An object of the invention is, therefore, to provide a circuit arrangement for ensuring the emission of a pulse group even when distorted binary values may occur.